<?php
$re = '/(?:(?!^)\G|({msg))\s+\K(?:\w+|\[[^][]*])(?=[^}]*})/';
$str = 'text {msg ru key} text text {msg key [m=1,p=1]} text {msg ru key [m=la la|p=1]} text';
$results = [];
$tmp = -1;
$tmp=$tmp+1;
} else {
$results[$tmp][] = $m[0];
}
}, $str);
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